Copper and other metals have been the primary materials used in the fabrication of pipes to be used in buildings. Advances in plastics technology, however, have resulted in the development of many new plastics, several of which are suitable for the fabrication of piping. For example, PVC, ABS and other plastic piping are now regularly used in the construction of buildings.
Although plastic piping is substantially less expensive than metal piping, plastic in general has a lower melting point than metal. In a fire, plastic pipes are therefore more likely to soften and deform or even melt.
Because pipes extend through holes in the ceilings, floors and walls of a building, if a portion of the pipe melts, the remaining portions will act like a chimney, allowing the fire to spread from floor to floor and room to room. As a result, the building codes of many cities and states require some fire separation device that will seal off the pipe in the event of a fire.
Fire-stop devices are known and have been disclosed in, for example, U.S. Pat. No. 4,788,800 (the '800 patent). The '800 patent, however, discloses a device that is an integral part of the wall or ceiling and is not a retrofittable fire-stop device that can be used in connection with an existing continuous section of pipe. Moreover, the device disclosed in the '800 patent requires the use of a fugitive metal coupling that joins two discrete pipes. Because such devices use a coupling, they are not retrofittable and cannot be easily modified to allow use with different diameter pipes
Another problem with known fire-stop devices is that the devices require the pipe or coupling to melt rather substantially before the fire-stop device will operate.
Accordingly, it is an object of the present invention to provide a fire-stop device that can be installed in connection with a pre-existing installation of a single continuous length of plastic pipe as well as installed in a new building construction.
It is another object of the present invention to provide a retrofittable fire-stop device that can be quickly and easily modified to be used in connection with several different diameters of plastic pipe.
Another object of the present invention is to provide a retrofittable fire-stop device that affirmatively cuts the plastic pipe in response to a fire and thereby seals the hole (in contrast to other known devices which require the pipe to melt rather completely before attempting to seal the hole).
Yet another object of the present invention is to provide a retrofittable fire-stop device in which the device only exerts a force on the pipe when the device is exposed to flame or heat.
Another object of the present invention is to provide a retrofittable fire-stop device in which a cutting member and other fire blocking means are not in contact with the pipe until the device is exposed to heat.
A further object of the present invention is to provide a retrofittable fire-stop device in which a cutting member cuts through the pipe, delivers fire-blocking material to the interior of the exposed pipe, and provides a support against which the fire-blocking material may expand and, in combination with the cutting member, block the mating pipe hole.
Other objects and advantages of the invention will become apparent upon reading the following detailed description of the invention and upon reference to the drawings. Throughout the drawings, like reference numbers refer to like parts.